Finding the Third Proportional to 21,357 and 42,690

Step by Step Solution

1. Step 1: Write the proportion equation
   21,357 : 42,690 = 42,690 : x
2. Step 2: Convert to fraction form
   21,357/42,690 = 42,690/x
3. Step 3: Cross multiply
   21,357x = 42,690 × 42,690
4. Step 4: Simplify right side
   21,357x = 1,822,436,100
5. Step 5: Solve for x
   x = 1,822,436,100/21,357
6. Step 6: Final answer
   x = 85,332.03